In GBIF bumblebee records with equal effort, European northern edges and North American southern edges moved north from 1901–1974 to 2018–2025; five-record limits follow record counts
Kerr et al. (2015, Science) reported that bumblebee northern range limits in North America and Europe did not move north, that southern limits moved north, and that species did not track warming. Their limit metric is the mean latitude of the five most extreme records. We tested this metric and an equal-effort alternative with GBIF record counts per geohash-4 cell for 111 Bombus taxa and the genus in six periods, 1901–2025 (tile totals agree with GBIF search counts). Within one set of records, the five-record northern limit of the median species moved 528 km (North America) and 724 km (Europe) when the sample increased from 50 to 5,000 records. Synthetic records with no range change gave raw shifts from −149 to +217 km. The equal-effort metric uses 1° cells with at least 10 genus records in both periods and the outer 10% of species occupancy. In synthetic data it had a bias of 16 km or less with no range change, and it recovered 61–114 km of a 111 km shift. At equal effort, northern edges in Europe moved north by +69 km (95% CI 21–120) by 1999–2010 and +88 km (8–162) by 2018–2025, while the raw metric gave −76 km for 1999–2010. Southern edges in North America moved north by +94 km (41–152) and +135 km (62–211), less than the raw +421 and +301 km. Northern edges in North America were not determined (−36 km, CI −172 to +73). From 1901–1974 to 2018–2025, the cool edge moved to cooler cells by 22% (CI 11–34%) of the local June–August warming in Europe and by 34% (13–54%) in North America. Results were similar with other effort thresholds, edge widths, taxonomies, and a 1975–1986 baseline, with exceptions that we report. Limits: GBIF data, not the original database; photo identifications and target-group effort can bias occupancy; the equal-effort metric under-reports northern shifts.
Bombus · bumblebee · range shift · range limit · sampling effort · GBIF · climate tracking · rarefaction · community science · re-analysis
References
4- challengesdoi:10.1126/science.aaa7031
We re-test its range-limit results with GBIF data and effort control; its five-record metric follows record numbers, and European northern edges moved north at equal effort.
- doi:10.1126/science.aax8591
Related bumblebee occupancy study from the same data source.
- usesdoi:10.1038/s41597-020-0453-3
CRU TS 4.09 monthly temperature for edge warming and thermal tracking.
- doi:10.5061/dryad.gf774
Original Kerr et al. (2015) data and code; not accessible without a Dryad token at retrieval time.
Cited by
1 publicationPublic catalog entries on Sciscape.
- Four effort-adjusted estimators on one GBIF bumblebee table agree that North American southern limits moved north from 1901–1974 to 2011–2025, but they disagree on European southern limits
Independent study of the same question. We re-implement an outer-10% equal-effort edge similar to its estimator; its European northern and North American southern results agree in direction with ours.